Abstract

The extended semantic realism (
ESR
) model proposes a new theoretical perspective which embodies the mathematical formalism of Hilbert space
quantum mechanics (QM) into a broader noncontextual, hence local, framework, reinterpreting quantum probabilities as conditional (in a nonstandard sense). We have proven in a previous paper that each generalized observable introduced by the ESR model is represented by a family of positive operator valued measures (POVM) parametrized by the pure states of the physical system Ω that is considered. We show here that each mixture is represented in the ESR model by a family of density operators parametrized by the physical properties characterizing Ω. This representation implies predictions that may differ from those of QM and avoids some deep problems that arise in the interpretation of mixtures provided by QM. We also show that the state transformations induced by idealized nondestructive measurements can be obtained by means of a nontrivial generalization of the Lüders postulate, and discuss our results in the special case of discrete generalized observables.